Step feeders are used to singulate and transfer workpieces from one location to another. Some step feeders include moving stairs interposed between fixed stairs, with the moving stairs driven by a motor and crank shaft. A log, cant, or other workpiece is deposited onto the lowest of the moving stairs, and the moving stair is driven upward to lift the workpiece to a fixed stair. The next moving stair lifts the workpiece from the fixed stair to the next consecutive fixed stair, and so on, until the workpiece reaches the desired location. Other step feeders have two sets of moving stairs. In step feed feeders of this type, one set of moving stairs is moved up while the other set is moved down.
In both cases, the moving stair that raises the workpiece has a fixed depth. Shallow stairs are suitable for singulating small workpieces, but larger workpieces may fall off the stairs during transport. Deeper stairs are more useful for singulating larger workpieces, but they may allow smaller workpieces to be carried on the moving stair in groups of two or more, making the stairs less suitable for singulating small workpieces.